Published: Saturday, June 21, 2014 at 6:01 a.m.

Last Modified: Friday, June 20, 2014 at 5:23 p.m.

Modern construction offers more energy-efficient buildings but also comes with one potentially deadly drawback: The air-tight structures are susceptible to radon gas buildup that can cause lung cancer with long-term exposure.

That is of particular concern in parts of Florida at higher risk of exposure, including much of western Alachua County, because of the rocky, clay soils that are rich in uranium that decays to produce the radioactive gas that enters homes through cracks in the foundation or through well water.

Radon is an odorless, colorless, tasteless gas that can be detected only by monitors. The U.S. Environmental Protection Agency estimates that it is responsible for more than 21,000 lung cancer deaths per year, second to smoking with 160,000 annual lung cancer deaths.

The Florida Department of Health says that one in five Florida homes has elevated radon levels — elevated levels being established at 4 picocurie per liter or more. The EPA singles out nine counties in particular at higher risk with an average indoor screening level of 2 to 4 pCi/L, including a swath of the Interstate 75 corridor that includes Columbia, Union, Alachua, Marion and Citrus counties. Leon, Hillsborough, Polk and Dade counties are also at higher risk.

Within Alachua County, a Florida Department of Health map shows the highest risk in parts of Gainesville, extending west toward Newberry and northwest along I-75 and into Alachua, where active radon controls such as vent fans are recommended.

No state requires home radon tests, and Florida is one of the few states to require testing of schools and child care centers, according to the National Conference of State Legislatures.

Florida also requires testing of 24-hour care facilities such as foster homes, nursing homes and prisons, and that building purchase or rental contracts include a notification that radon gas levels that exceed federal and state guidelines have been found in buildings in Florida.

The EPA recommends testing buildings and constructing venting systems for those with elevated radon levels. Home test kits that cost as little as $10 are available from hardware stores and major retailers, and professionals with more data-intensive monitors are available for hire.

According to the state’s June 5 listing, Land Environmental Group is the only company based in Alachua County that is state certified to offer radon measurement and radon mitigation services.

Dawn Howell, who owns the business with her husband, Kurt, said buildings should be tested every few years because radon levels can change over time. Levels also can vary drastically from house to house, and from room to room, she said.

Howell said about 90 percent of the buildings they have tested measured 4 pCi/L or higher.

“We seem to find the highest levels along Hogtown Creek,” she said.

The company has a crew of three or four people installing mitigation systems in new and old construction every day at apartments, homes, schools, prisons and businesses, and is booked up a month out, she said.

Mitigation involves drilling a hole in the slab and installing a 3-inch diameter pipe that runs through a closet or a wall into the attic and through the roof, with a vent fan to suck the radon up through the house.

Howell said the average home system includes two or three vents and costs $2,200 to $2,700. A rule of thumb is to install one pipe for every 1,000 square feet and each addition that has a separate slab.

Home inspector Don Gocek of Santa Fe Inspection Service said about 20 percent of local home buyers will ask for a radon test, particularly young couples with small children and people from northern states where the radon risk is higher.

Gocek uses an electronic monitor that takes measurements over 48 hours and can detect whether the monitor was moved or windows and doors were opened in case a home seller tries to cheat the test.

He said he has measured readings ranging from the 20s to the 60s in homes around the University of Florida, in the 50s along Northwest 39th Avenue, and ranging from 3 to 8 in Haile Plantation, while Howell said her company regularly gets 12 pCi/L in Haile.

The highest readings tend to be in the 32605 and 32606 ZIP codes, Gocek said.

“The highest reading I ever had was behind the Gainesville High School area. An 89.7 was the average,” he said.

Gocek said the levels are higher when the earth is cooler — at night or in the winter.

Larry Condra had a mitigation system installed in his home in the Duck Pond area that he said brought levels from 7 to 0.4 pCi/L.

He had searched the Internet for possible environmental factors for a family member’s thyroid cancer and decided to get the radon test after finding articles speculating about a possible correlation.

“It cost me around $1,900, but it’s well worth it rather than sitting around wondering whether there’s some kind of radioactive isotope going down into my lungs that’s going to give me lung cancer somewhere down the road,” he said.

He said a friend to whom he mentioned the test decided to test her own home, which measured 30 pCi/L.

“She said that’s really weird because you spend your whole life trying to eat right, exercise, don’t do anything unhealthy and you’re sitting in a house that’s toxic, literally,” Condra said.

TJ Morrissey said the fan stopped working on the radon system in his rented home in Haile Plantation, and the home tested 15 times the acceptable radon level. His family moved out on May 31 when the lease was up and the owner decided to sell.

“Since we moved out of there, we all felt better,” he said. “I don’t know if it was radon, or dust, or mold or whatever.

“I think in the future I’d try to find out a little bit more about radon before renting or owning a place that might have high levels.”

Gocek said he has seen people back out of buying a house because of radon tests, “but it can be fixed. That’s what I try to tell them.”

For new construction, the EPA recommends passive radon-resistant measures — as opposed to the active electric fan — that include a four-inch layer of gravel below the foundation to disperse the gas, heavy duty plastic sheeting on top of the gravel to prevent radon from entering the house, a vent pipe that runs from the gravel layer through the roof, and sealing and caulking of all openings and cracks in the foundation and walls.

In addition to entering through cracks in the foundation, Gocek said radon also can enter through water that has not been aerated.

“For people with private wells, that could be an issue that’s often overlooked,” he said.

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